Long-term differences in young adults' sexual behavior and adjustment following preadolescent sibling and nonsibling peer childhood sexual experiences were investigated. Questionnaire data were collected from 526 undergraduate college students. Of this sample, 25 (5%) reported having had only a sibling sexual encounter, 61 (12%) reported having had both a sibling and a nonsibling childhood sexual experience, 236 (45%) reported having had only a nonsibling sexual experience, and 204 (39%) reported no sexual experience with another child prior to age 13. No differences were found between the sibling, nonsibling, and no-experience groups on a variety of adult sexual behavior and sexual adjustment measures, including incidence of premarital intercourse, age at first intercourse, number of intercourse partners, sexual satisfaction, sexual arousal, and sexual dysfunctions. It was concluded that adult sexual adjustment is not negatively or positively influenced by typical early childhood sexual experiences among similar-aged siblings.